Possible encapsulation material?

[Mike90250]

Finally I tried mineral spirits.
I worked great!
You do have to be careful not to whip in bubbles.

A simple vacuum bag can get rid of the bubbles, and make a tighter sandwich, if it's all flat, nothing will crack, but if tab wire is thick, and lumps of solder, that will shatter cells as the vacuum flattens everything out. Or wip up your thinned mix, vacuum the air bubbles out, and then pour.

[longwolf]

Here's an update.
I've done some testing where I only used the CS (Clear Seal) to seal the edges of my test 'cells'.
I've heated them under my windshield, soaked them in water, frozen them and heated them again.
And there's no sign of vapor between the pains of glass!

Today I began tests on thinning the CS.

First I tried acetone. It thinned it, but then it turned milky.
Next it reacted with the CS and kind of turned it into a foam.
One thinner down.

Next I tried denatured alcohol.
Again, it turned the CS white.
But it wouldn't thin or even mix with the CS.

Finally I tried mineral spirits.
It worked great!
You do have to be careful not to whip in bubbles.
I poured some on a piece of glass and placed a smaller piece on it. It looks about like water between the pains. If/when it drys, I'll test it with a light meter.

[longwolf]

...Perhaps you could put some fine copper wire on a glass plate and cover it with this clear seal stuff and then wait several months to see if the copper corrodes?.....

Well, I don't have months to wait.
I'm living out of my van and need the power months ago.
Also, I'd rather not have the cells bouncing around in their box any longer than they have to

I don't believe the Clear Seal is a silicone based rubber.
The tube lists a number of benzene compounds.
It also says, "Stays crystal clear, Will not yellow, Weatherproof, indoor/outdoor use and 50 year durability"

Mike says the electronics grade silicone uses an acetone cure, I believe I've read that slyguard is an alcohol cure.

I'm just looking for advise on the safest solvent for thinning.

[muskrat]

what does clear seal put out when it cures?

Regular home silicone rubber will work for a few months before the acetic acid causes corrosion.It will do a good job of sealing the cells from water but the problems come later.Perhaps you could put some fine copper wire on a glass plate and cover it with this clear seal stuff and then wait several months to see if the copper corrodes? I was thinking of using polyester resin which is very sunlight resistant but that would only work on the back of the cells since anything on the front would not dry.I was also considering a very high melting point wax but I doubt it would be clear enough for the front of the cell.The wire from a old set of headphones is very thin and might show any corrosion quickly.

[longwolf]

Id try it on a single cell, and see what the shrinkage does.

Great idea!
Instead of wasting a cell, I got some cheap picture frames from a dollar store.
One 8.5x11 as the glass and two 4x6's to use as simulated solar cells.
I cut one of the 4x6's in two so I would also have a T intersection/joint.

I used the Clear Seal which is a synthetic rubber.
My first attempt failed because I only gave it 12 hours to dry. The spec sheet says 5 days to a full cure.

But the second try is working well. I placed some black paper under the glass and put the whole thing in between my windshield and a reflective sun screen.
After several hours of pointing at the Texas summer sun, they were too hot to touch.
But I still tried to gently push the 'cells' around on the glass. They held firm!

I plan to try soaking them in water then freezing and reheating them several times as a full test.

There was shrinkage, but it just got thinner without pulling away from the edges of the glass.

This stuff is very clear. If I can thin it enough, I think it could be used like slyguard.

Question, I need a thinner that won't hurt the cells. The Clear Seal says to clean up with mineral spirits but I think acetone or denatured alcohol might work as well.
Would any of those be safe?

I have a light meter so I'll be able to measure how much difference having the Clear Seal between the plates will make.

[phillam]

I think everyone would love that miracle cheap product (well except companies like DuPont that is). Seems to me if the method is cheap you are always sacrificing in one area.

That probably applies to what I am attempting...especially when I am going for around $15 per panel (encapsulation). The traditional techniques put DIY panels out of my range so I am trying to think out of the box. I also have a budget limit based on govt rebates I am working within to make a cost netural system.

Al-Foil ( or really thin al sheeting) has some great properites: reflectivity, heat dissipation, malleability, (almost) no vapour permeability and cheap! There are obviously bad properties as well but I am working on these.

At the moment I am focussing on the big killers; moisture ingress, heat dissipation, varying thermal expansion and price. Anyway I'm planning a range of tests in the coming weeks so I will let you know how I go with the process.

Whilst I am here does anyone know of a 2 part adhesive with good UV/heat tolerant properties? Epoxy was my first thought but I am not happy with it's poor UV stability especially when we are talking solar panels. I am not intending to encapsulate just using as a light adhesive within the panel. Polyurethanes look better for UV but I am not sure of heat and adhesion.

I'm not committed to silicone, just tying to find something I can afford
What do you think your method will cost you per panel?

[longwolf]

regular household silicone rubber produces acetic acid when it cures.This will swiftly corrode electrical connections.This is why it is never used for sealing electrical connections.

Mike mentioned that a vinegar smell meant you'd do damage.
I believe he said an acetone base silicone was safe.

LiquidNails says that their LS-205 uses a Acetoxy cure.
I was hoping that was some type of acetone cure.
Are you saying Acetoxy produces acetic acid?

Maybe I'll have to try their CS-145 instead.

[muskrat]

regular silicone rubber produces acetic acid

regular household silicone rubber produces acetic acid when it cures.This will swiftly corrode electrical connections.This is why it is never used for sealing electrical connections.

[longwolf]

Longwolf,

... so I am testing something else at the moment using commercial grade al-foil and vacuum adhering. (all DIY stuff).....

I'm not committed to silicone, just tying to find something I can afford
What do you think your method will cost you per panel?

[phillam]

Longwolf,

from what I have read vapour tansfer (ie water entry) is the major issue in encapsulation. I am not sure of the specific vapour permeability of the silicon you reference but there is some research on specific silicon products that show silicon to be a poor membrane and when you are talking about a large surface area it might be an issue. I suppose it depends on the life you are after of your cells. Short term shouldn't be a problem but long term it could reduce your output considerably.

I looked at a similar concept using flexible water membranes such as those used in pond linings and bathroom sealers but I was concerned about the premeability so I am testing something else at the moment using commercial grade al-foil and vacuum adhering. (all DIY stuff).

I would be interested in how you go with the pouring if you try it.

Good luck!

[longwolf]

Thx Mike,

I may have found a better one on their site.
It's a silicone with an Acetoxy cure.

LIQUID NAILS

[Mike90250]

Maybe, depends on the product's shrinkage as it cures.

Clear Seal All Purpose Sealant (CS-145)

From their PDF, it's 58% solids, and 47% shrinkage as it cures. Id try it on a single cell, and see what the shrinkage does.

[longwolf]

I was considering using silicone to seal cells directly to the glass, when I ran across one of Mikes posts where he warns to only use electronics grade silicone.
Pricing the stuff, you may as well go with Slyguard.

But then I spotted this from Liquid Nails:

http://www.liquidnails.com/products/product.jsp?productId=5

What do y'all think, could it work?